1. Open market sale pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 15, 2017, at which time the trading schedule, including sale periods, price and the number of shares to be sold, was established in accordance with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended.

2. 25% of the total number of shares subject to this option vested on September 3, 2014, and the remaining shares subject to the option vested and became exercisable in equal monthly installments over the 36 months following the initial vesting date.

3. On May 15, 2018, the reporting person paid the exercise price and exercised options to purchase 5,000 shares of the company's common stock. These shares have not been sold and are held for the account of the reporting person. The options exercised in this transaction have the same vesting terms described in footnote 2.